睡眠は複雑な出来事を思い出す能力を向上させる(Sleep improves ability to recall complex events)

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2024-02-20 ミュンヘン大学(LMU)

睡眠が複雑な関連の記憶に及ぼす影響を調査した研究では、睡眠中に特に弱い関連を強化し、学習時に直接関連のなかった要素間の新しい関連を築くことが示された。睡眠後の記憶能力は、睡眠中の脳活動であるスリープスピンドルと関連しており、これが記憶内容の活発な強化をもたらすことが示唆された。このような記憶の強化は、人間の脳の重要な適応であり、環境の一貫した理解を促進し、将来の出来事に対する包括的な予測を可能にする新しい機能であると考えられる。

<関連情報>

睡眠は多要素事象記憶におけるパターン完成の基礎となる連想構造を形成する Sleep shapes the associative structure underlying pattern completion in multielement event memory

Nicolas D. Lutz, Estefanía Martínez-Albert, Hannah Friedrich, +1, and Luciana Besedovsky
Proceedings of the National Academy of Sciences  Published:February 20, 2024
DOI:https://doi.org/10.1073/pnas.2314423121

Significance

Real-life events usually consist of multiple elements such as a location, people, and objects that become associated during the event. Such associations can differ in their strength, and some elements may be associated only indirectly (e.g., via a third element). Here, we show that sleep compared with nocturnal wakefulness selectively strengthens associations between elements of events that were only weakly encoded and of such that were not encoded together, thus fostering new associations. Importantly, these sleep effects were associated with an improved recall of the complete event after presentation of only a single cue. These findings uncover a fundamental role of sleep in the completion of partial information and are critical for understanding how real-life events are processed during sleep.

Abstract

Sleep supports the consolidation of episodic memory. It is, however, a matter of ongoing debate how this effect is established, because, so far, it has been demonstrated almost exclusively for simple associations, which lack the complex associative structure of real-life events, typically comprising multiple elements with different association strengths. Because of this associative structure interlinking the individual elements, a partial cue (e.g., a single element) can recover an entire multielement event. This process, referred to as pattern completion, is a fundamental property of episodic memory. Yet, it is currently unknown how sleep affects the associative structure within multielement events and subsequent processes of pattern completion. Here, we investigated the effects of post-encoding sleep, compared with a period of nocturnal wakefulness (followed by a recovery night), on multielement associative structures in healthy humans using a verbal associative learning task including strongly, weakly, and not directly encoded associations. We demonstrate that sleep selectively benefits memory for weakly associated elements as well as for associations that were not directly encoded but not for strongly associated elements within a multielement event structure. Crucially, these effects were accompanied by a beneficial effect of sleep on the ability to recall multiple elements of an event based on a single common cue. In addition, retrieval performance was predicted by sleep spindle activity during post-encoding sleep. Together, these results indicate that sleep plays a fundamental role in shaping associative structures, thereby supporting pattern completion in complex multielement events.

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